public void RemoveNeighboursTest()
{
Node <City> ct = new Node <City> (new City("war", "maz", "24351"));
n.AddSuccessor(ct);
n.AddPredecessor(ct);
ct.RemoveNieghbours();
Assert.True(ct.predecessors.Count == 0);
Assert.True(ct.successors.Count == 0);
Assert.True(n.predecessors.Count == 0);
Assert.True(n.successors.Count == 0);
}